A system for keyless locking of a firearm against discharge is provided, which includes a casing configured for removable insert into a barrel of the firearm, and an extension rod disposed in longitudinally displaceable manner therein. The extension rod is provided with first and second ends and an intermediate portion extending longitudinally therebetween. A locking component supported by the casing is displaceable responsive to the extension rod between locked and unlocked positions. A powered driver coupled to the extension rod for selectively drives the displacement thereof responsive to user activation. The locking component in the locked position protrudes transversely beyond the casing for retentively engaging an inner surface of the firearm to prevent removal of the casing from its barrel, and in the unlocked position is retracted to maintain clearance from the inner surface of the firearm to permit removal of the casing from the barrel of the firearm.